A customer segment = a group of people with shared needs.
This is a core marketing principle.
Notice that no mention is made of demographic information (B2C) or job titles (B2B).
If you have a clear understanding of the customer segments that you are communicating with, your marketing will be more effective.
There will be higher levels of message repetition.
Customers will get a better feeling about you, as your messages will be relevant to them.